Pressure-sensitive copying papers

ABSTRACT

3-(R1-N(-R2-),7-(R4-N(-R3-)SPIRO(PHTHALAN-1,9&#39;&#39;-XANTHENE)   WHEREIN R1 AND R2 EACH IS AN ALKYL GROUP HAVING FROM 1 TO 5 CARBON ATOMS, WHEREIN R3 IS AN ACYL GROUP, AND WHEREIN R4 IS AN ARYL GROUP IS DISCLOSED.   A PRESSURE SENSITIVE COPYING PAPER CONTAINING A COLOR FORMER HAVING THE GENERAL FORMULA

United States Patent Office I 3,669,712 Patented June, 13, 1972 3,669,712 PRESSURE-SENSITIVE COPYING PAPERS Shiro Kimura, Teruo Kobayashi, and Sadao Ishige, Kanagawa, and Masataka Kiritani, Shizuoka, Japan, lassignors to Fuji Photo Film Co., Ltd., Kanagawa, No Drawing. Filed June 26, 1970, Ser. No. 50,303 Claims priority, application Japan, June 27, 1969, 44/50 819 US. Cl. 117--36.2 3 Claims ABSTRACT OF THE DISCLOSURE A pressure sensitive copying paper containing a color former having the general formula wherein R and R each is an alkyl group having from 1 to carbon atoms, wherein R is an acyl group, and wherein R is an aryl group is disclosed.

BACKGROUND OF THE INVENTION (1) Field of the invention This invention relates to a pressure-sensitive copying paper. More particularly, this invention relates to a pressure-sensitive copying paper using a novel color former.

(2) Description of the prior art Generally, a pressure-sensitive copying paper consists of a combination of an upper sheet prepared by dissolving an electron acceptive, color forming and almost colorless organic compound (hereinafter, such organic compounds are described as color former) in an organic solvent, encapsulating the solution as microcapsules, and applying the microcapsules to a support and a lower sheet prepared by applying an electron donating solid acid to another support. In some cases, the pressure-sensitive paper is composed of a combination of the upper sheet, the lower sheet, and an intermediate sheet prepared by applying microcapsules containing an organic solvent solution of the color former to one surface of a support and applying the solid acid to the other surface of the same support.

Further, a pressure-sensitive paper of a type in which the microcapsules as described above and the solid acid are applied to one side of a support as a mixture thereof or as two layers is known.

In use, in the pressure-sensitive paper using a combination of two or more sheets, the sheets are piled so that the microcapsule layer is contacted with the layer of the solid acid and they are pressed locally. In the single sheet type of pressure-sensitive paper, the coated layer is locally pressurized, whereby the microcapsules are ruptured and the dye solution in the microcapsules is contacted with the layer of the solid acid to form a color at the locally pressurized portions.

As the solid acid, such inorganic acid materials as bentonite, zeolite, acid clay, active clay, magnesium trisilicate, and the like, and organic acid materials such as benzoic acid, benzene-sulfonic acid, naphthol, and the like, are used.

,.As the color formers, Rhodamine Lactone, Rhodamine Anilinolactam, and the like, are known.

However, the known color formers, with a red forming property have the following disadvantages. That is to say, since Rhodamine Lactone itself is unstable, when it is in a natural atmosphere, it is colored in a short period of time, i.e., it is spontaneously colored before it is contacted with the solid acid (hereinafter, the phenomenon is designated as color forming fog). On the other hand, with Rhodamine Anilinolactam, it takes a considerable amount of time before it is completely colored when the. color former is contacted with the solid acid.

In general, the color former used for pressure-sensitive copying papers is required to have properties such that the color former is colorless before it reacts with the solid acid on contact therewith and is stable in the atmosphere without forming a fog, and the color former is colored instantly when it is contacted with the solid acid. The colored image obtained has a high color density and also excellent light fastness and water resistance. The abovedescribed conventional color formers are deficient in these respects.

Therefore, an object of this invention is to provide a pressure-sensitive copying paper in which a compound having excellent properties is used.

SUMMARY OF THE INVENTION The color former used in this invention has the following general formula wherein R and R each is an alkyl group having from 1 to 5 carbon atoms, wherein R is an acyl group, and wherein R is an aryl group. 1

The important feature in the structure of the compound shown by the above general formula is that the amino group at the 7-position is substituted with an acyl group or an aryl group. 7 v

Specific examples of the above-described color formers used in this invention are shown below.

a. 4 procedure is extracted with acetone concentrated and dried to give the compound.

and the extract is General form la Color The general synthesis of the color formers mentioned above can be as follows:

wherein R R R and R are as above described. That is to say, 1 mol of Intermediate A, an o (4-dialkylamino- Z-hydroxybenzoyDbenzoic acid and 1 mol of Intermedi ate B, a p-(N-acyl-N-arylamino)phenol are subjected to a condensation reaction for from 3 to 50 hours at from 20 to 90 C. in the presence of 'a dehydrating agent, such as sulfuric acid, fuming sulfuric acid, phosphoric anhydride, anhydrous zinc chloride, and phosphorus oxy-' chloride. The reaction liquid is poured into a large amount of ice water, and then an aqueous alkaline solution such as an aqueous sodium hydroxide solution is added to the mixture to make the resultant mixture Weakly alkaline. The desired material precipitated by the above Intermediate A and Intermediate B used above can also be prepared in the following manner:

Intermediate A can be prepared by a known manner, for example, by refluxing under heating 1 mol of metadialkylamino-phenol and 1 mol of phthalic anhydride in toluene for a few hours as described in Friedlander, vol. 4, page 260. Also, Intermediate B can be prepared by a known method, for example, by subjecting an aniline and hydroquinone to a dehydration condensation to give a p- (N-arylamino) phenol according to the following reaction formula,

cone. H2804 lam-124+ no on HO-Q-N-AR;

wherein R is an aryl group, and by acyl ating the above product in a conventional manner as shown in Chemical Abstracts, 52, 7184.

The synthesis of each color former used in this invention'is described in the following:

SYNTHESIS 1 (COLOR FORMER 1) 1 mol of o-(4-diethylamino-Z-hydroxybenzoyl)benzoic acid having the structure of Intermediate A, in which R is C H and R is C H and 1 mol of p-(N-acetoanilino)- phenol having the structure of Intermediate B, in which R3 is were condensed for 24 hours at about 50 C. in 10 mols of concentrated sulfuric acid. Thereafter, ice Water was and R is poured into the reaction product, the mixture was made weakly alkaline with sodium hydroxide, and the product was extracted with toluene, concentrated and dried to obtain 3-diethylamino 7 '(-N-acetoanilino)-fluoran as an amorphous solid product.

SYNTHESIS 2 (COLOR FORMERS 2-10) Absorption of color former (m X1 X2 N3 For manufacturing the pressure-sensitive paper of this invention using the color former described by the above general formula, the methods described in the specifications of US. Patent Nos. 2,548,366, 2,800,457, and 2,800,458, are suitable, namely, by producing microcapsules utilizing composite coacervation. However, the feature of the present invention is the use of the compound shown by the above-described general formula and the properties of the pressure-sensitive paper, are not infiuenced by the manner of producing the same. Thus, there are no limitations in the manner of manufacturing the pressure-sensitive paper in this invention. The amount of the color former is usually used in the range of from 1 to 5% by weight to an oily solvent.

The pressure-sensitive paper of this invention is colorless before color forming reaction and is stable under atmospheric conditions unaccompanied by the formation of spontaneous color fog. When the pressure-sensitive paper is colored on pressing, the color image is formed instantaneously or the color forming speed is extremely high. Moreover, the color density of the copied image is high and the image has excellent light fastness and water resistance. Also, since the color thus formed has an absorption in the spectral region of from about 350 to 420 III 1., which corresponds to the light-sensitive region of a diazo light-sensitive paper, the copied image can be copied on a diazo light-sensitive paper.

The color former corresponding to the above-described general formula is a red-forming dye but by mixing the color former with other known yellow-, purple-, blue-, or green-forming color formers, a pressure sensitive copying paper giving rise to various colors can be prepared.

Example 1 3 g. of the color former 1 was dissolved in 100 g. of diphenyl trichloride and the solution was emulsified by adding thereto an aqueous solution of 20 g. of gum arabic in 160 g. of water. Then, an aqueous solution of 20 g. of acid-treated gelatin in 160 g. of Water was added to the emulsion. After reducing the pH of the emulsion to 5, 500 g. of water was added thereto to cause coacervation, whereby dense liquid films of gelatin and gum arabic were formed around the oil drops in which the color former had been dissolved. Subsequently, the pH was reduced to 4 and then 4 g. of 37% Formalin was added for hardening. During the above procedures, the temperature of the system was kept at 50 C. but then the system was cooled to C. for gelling the dense liquid films. The pH was increased to 9 for increasing the hardening effect,

and then the system was allowed to stand for a few hours, whereby the encapsulation operation was finished.

The capsule-containing liquid thus obtained was applied to a paper by a coating manner, such as roll coating or air knife coating, and dried. The upper paper produced was placed on a clay paper (a lower paper prepared by applying a clay material to a paper) and they were pressed locally by writing, whereby a red record is instantaneously obtained on the clay paper.

When the red dye record thus formed was wet with water or was exposed to sunlight for a long time, no fading occurred. Also, when the upper paper was heated to C. for 20 hours and exposed to sunlight for a long time, the color forming power of the upper paper was not reduced. Thus, the pressure sensitive paper of this invention showed sufficient light fastness and water resistance before and after color forming for practical use.

Example 2 The same procedure as used in Example 1 was followed using each of the color formers 2-10 instead of the color former 1. The results showed that in each case of using the color former, a red record was instantaneously formed on a clay paper. Also, the properties of the pressure sensitive paper before and after color forming were excellent as in Example 1.

What is claimed is:

1. A pressure-sensitive copying paper comprising a support having coated thereon a layer of microcapsules containing a fluoran compound having the following general formula wherein R and R each is an alkyl group having from 1 to 5 carbon atoms, wherein R is an acyl group, and wherein R is an aryl group, a second support having coated thereon a layer of an electron donating solid acid, whereby a distinct color is produced on contact of said fluoran compound with said acid.

2. The pressure-sensitive copying paper as claimed in claim 1, wherein said fluoran derivative is a member selected from the group consisting of 3-diethylamino-7- N-acetoanilino) -fluoran, 3-dimethylamino-7- (N-aceto-p-toluidino -fiuoran,

3 -diethylamino-7- (N-aceto-m-toluidino) -fluoran, 4-diethylamino-7- (N-aceto-o-toluidino -fluoran, 4-diethyl amino-7 N-aceto-m-xylidino) -fluoran, 3-diethylamino-7- (N-aceto-o-anisidino) -fluoran, 3-diethylamino-7- (N-aceto-p-anisidino -fluoran, 3-N-ethyl-N-isopropylamino -7- (N-acetoanilino) -fluoran, 3-diethylamino-7- N-benzoylanilino) -fluoran, and 3-diethylamino-7- (N-benzoyl-p-toluidino -fluoran.

7 13. A pressure-sensitive copying paper comprising a sup: port having coated thereon a layer of microcapsules containing a fluoran compound having .the following general formula, v 7

to 5 carbon atoms, wherein R is an acyl group, and

wherein R and R each is an alkyl group having from 1 15 wherein R4 is an aryl group, and a layer of electron donating solid acid coated 'on said support whereby a distinctcolor is produced on contact of said fluoran compound With said acid.

References Cited UNITED STATES PATENTS 3,501,331 3/1970 Kirnura et a1 117--36.8 3,514,310 5/1970 Kimura et a1. 11736.2 5/19 70' Kimura et a1 117'36.2 

